Ion pairs, in water

A Global scheme for solvolysis 2 Clocks for reactions of ion pairs 3 Addition of solvent to carbocation-anion pairs i Protonation of a carbocation-anion pair 11 Isomerization of ion pair reaction intermediates Reorganization of ion pairs in water 13 Internal return of isotopically labeled ion pairs Racemization of ion pairs 22 Concluding remarks 24 Acknowledgements 24 References 24... 

Kollig, H.P., Ellington, J.J., Weber, E.J., and Wolfe, N.L. Environmental research brief - Pathway analysis of chemical hydrolysis for 14 RCRA chemicals. Office of Research and Development. U.S. EPA Report 600/M-89/009, 1990, 6 p. Kolthoff, I.M. and Chantooni, M.K., Jr. Crown ether complexed alkali metal picrate ion pairs in water-saturated dichloro-methane as studied by electrolytic conductance and by partitioning into water. Effect of lithium chloride on partitioning, J. Chem. Eng. Data, 42(l) 49-53, 1997. 

Reorganization of ion pairs in water 13 Internal return of isotopically labeled ion pairs 18... 

From (4-26), for a 1 1 electrolyte in water the Bjerrum critical distance is 3.6 X 10 cm. When it is realized that ions in water are normally highly solvated and that the sum of ionic crystal radii for typical anions and cations often approaches or exceeds 3.6 x 10 cm, it is reasonable to find that dissociation constants for ion pairs in water are large thus for sodium hydroxide the dissociation constant is about 5. On the other hand, for a 2 2 electrolyte in water the critical distance is 14.3 x 10 cm, and for a 1 1 electrolyte in ethanol, 11.5 x 10 cm. In these cases, even highly solvated ions can readily approach to the distance necessary to form an ion pair. For magnesium sulfate the dissociation constant in water is 6 x 10 , and for sodium sulfate, 0.2. 

A9.6.4.9.2 Values of log Kow can be calculated for pentachlorophenol and similar compounds, both for the ionized and unionized (neutral) forms. These values can potentially be calculated for certain reactive molecules (e.g. benzotrichloride), but the reactivity and subsequent hydrolysis also need to be considered. Also, for such ionizable phenols, pKa is a second parameter. Specific models can be used to calculate log Kow values for organometallic compounds, but they need to be applied with caution since some of these compounds really exist in the form of ion pairs in water. 

Since the resultant cobalt(II) complex undergoes two types of conversions, one of which (Reaction 143) results in the initial product, the quantum yield of the photocatalytic reaction is lower than those of nonmacrocyclic complexes. The quantum yields of the irradiated [Co(sep)]3+ cation in 50% methanol and the irradiated [Co(diAMsar)]3+ cation in water and 33% methanol are of the same order of magnitude as that for the [Co(sep)]3+...I ion pair in water. The quantum yields of the complexes examined markedly change. The [Co(diNOsar)]3+, [Co(diAMHsar)], and [Co(diNOsar-H)]2+ cations proved to be the... 

E. Guardia, R. Rey and J.A. Padro, Potential of mean force by constrained molecular dynamics a sodium chloride ion pair in water, Chem. Phys., 155 (1991) 187-195. 

Under the circumstances it seemed desirable to obtain a pmf for TBC in water, though only the ion-pair region has been considered so far. The most closely related previous effort was by McCammon et al., who obtained a pmf for Na Cr in TIPS2 water and analyzed the dynamics for the Na Cr Na" //Cr barrier crossing. They used MD with importance sampling in this study, which is the only prior MC or MD determination of a pmf for an ion pair in water. Recently Pettitt and Rossky have calculated pmfs for several alkali halides in water via extended RISM theory. The qualitative accord with the MD results for Na Cl" is fine however, the XRISM pmf is much flatter. 

Figure 6. (a) (CHjjjC Cl" contact and (6) solvent-separated ion pairs in water at C-Cl separations of 3.00 and 5.75 A. Water molecules with oxygens within 4.5 A of any atom of the solute are shown. Taken from arbitrary configurations of the MC simulations. 

Indicate which compound in each of the following pairs is more likely to form ion pairs in water (a) NaCl or Na2S04, (b) MgCl2 or MgS04, (c) LiBr or KBr. 

For the weakly coupled limit, based on outer-sphere self-exchange reactions or ion-pair spectra (see Tables 1 and 2). Estimated metal-to-metal distance in contact ion pair.In water vs. S.H.E. except as indicated. Formally a Ru (NH3)5/Ru (NH3)5 (terminal/terminal) MMCT transition. There may not be a great deal of metal-metal charge-transfer character in this transition. Ru /pz MLCT/Ru H3)5 in [(Ru (NH3)5 2(pz[Ru XNH3)4]pz)] . In water vs. S.C.E. Formally, a central-to-terminal transition in [(Ru (NH3)5 2(pz[Ru (NH3)4]pz)]. This is necessarily a transition from the symmetric combination of Ru (NH3)5 and Ru (NH3)4 moieties in the ground state to an antisymmetric combination in the MMCT excited state." See the discussion of thr center-thr lectron systems in Section 7.11.4.1.1. Central metal... 

Free energetics of Nal contact and solvent-separated ion pairs in water clusters ... 

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